Internal combustion engines are commonly used on mobile platforms (to propel vehicles such as cars, trucks, airplanes, motorcycles, jet skis, snowmobiles), in remote areas (such as for oil well pumps or electric generators) or in lawn and garden tools (such as lawnmowers, weed-eaters, chainsaws, and more). There are various types of internal combustion engines, furnaces, boilers, kilns and gasifiers.
Spark type engines utilize a volatile fuel, such as gasoline. A spark plug provides the source of ignition. A typical fuel is gasoline as either reformulated to meet mandated urban air quality standards or a non-oxygenated gasoline typically sold in rural areas. High performance spark type engines are sometimes tuned to operate on pure methanol or ethanol. Compression type engines take in air and compress it to generate the heat necessary to ignite the liquid fuel. Typical high compression engines also utilize longer-chained petroleum-based diesel fuel, synthetically produced diesel fuel or bio-diesel fuels produced from either animal fats or plant oils.
When gasoline is burned, it produces pollutants in the form of hydrocarbons (HC), including nitrogen oxides (NOx), carbon monoxide (CO) and soot (particulates). In addition, gasoline in warm climates tends to evaporate due to the presence of volatile organic compounds (VOCs).
Internal combustion diesel engines are commonly used in vehicles operating both on-road for transportation and in off-road configurations for construction.
Furnaces and boilers are typically used for home or space heating, electrical generation or propulsion of large ships. Kilns are drying devices. Smaller kilns are used in the manufacture of pottery and ceramics. Larger kilns are used to dry lumber or to manufacture cement. Gasifiers are devices which convert solid carbonaceous fuels into synthesis gas mainly CO & H2 which is either combusted for heat or electricity, or further catalyzed into liquid chemical or fuel products.
When refined petroleum fuels, heavy crude oils, bitumen, petroleum coke or coal are combusted, these hydrocarbons produce pollutants which include nitrogen oxides (NOx), carbon monoxide (CO) and soot (particulates). Nitrogen oxides and volatile organic components react together in sunlight to form ground level ozone, a component of smog. Diesel has less of a tendency to evaporate than does gasoline. Lower distillate crude oils, bitumen, heating oils, bunker oils, coke or coal have even less tendency to evaporate VOC's.
In areas of high use, such as heavy automobile traffic, exhaust emissions from internal combustion engines, furnaces, boilers or kilns plus evaporation from the fuel tanks result in significant air pollution. In some urban areas, a brown haze of pollution frequently remains within the first several hundred feet off of the ground.
Alcohol fuels have come into use for internal combustion engines as a biodegradable, oxygenated fuel to further increase combustion efficiencies of petroleum-derived fuels in order to reduce harmful emissions. In the 1970's, gasohol, a blend of mostly gasoline with some fermented ethanol, was introduced in the United States during the Arab oil embargo to extend supplies of domestic gasoline. Unfortunately, at that time, many of the elastomeric engine seals, hoses and gasket components were designed only for gasoline or diesel and deteriorated with the use of solvent ethanol. Since then, engines, gaskets and fuel delivery systems have become equipped with fluorinated elastomers, which are tolerant to the greater solvent characteristics of oxygenated alcohol fuels.
Currently in 2012, the primary alcohol fuel is ethanol, which is typically fermented from grain (corn, wheat, barley, oats, sugar beets or sugar cane). Other versions of ethanol are now being produced through conversion of lignin and cellulose obtained from plant stalks or wood chips and termed as ligno-cellulosic ethanol employing extra acidic enzymes, a longer fermentation cycle and typically outputting only about ⅓ the ethanol volumes of fermented corn kernels or via gasification of lignin and cellulose conversion of syngas to ethanol.
The ethanol is typically blended into gasoline in various quantities. “Premium” gasoline, with a higher (Research Octane+Motor Octane)/2 (also known as (R+M)/2) octane rating than “regular” gasoline, is primarily gasoline with 10% to 15% volumes of ethanol (C2 alcohol). Another ethanol fuel is E-85, which is 85% ethanol and 15% gasoline. Still another alcohol fuel is M-85, which is 85% methanol (C1 alcohol) and 15% gasoline.
Grain ethanol is expensive to produce. Ligno-cellulosic ethanol is even more expensive to produce. Furthermore, producing sufficient quantities of grain ethanol to satisfy the needs of the transportation industry is not practical because traditional food crops are diverted into fuel. Traditionally, governments have heavily subsidized grain ethanol. Droughts and government policy towards farming in general (less intervention and payments to farmers) make the supply of grain ethanol's availability and future uncertain and expensive.
In addition, both (C1) methanol and (C2) ethanol (defined as lower alcohols) have less energy content when compared to gasoline. Methanol contains about 56,000 BTU's/gallon and ethanol contains about 75,500 BTU's/gallon while gasoline contains about 113,000 BTU's/gallon. A motorist notices this when a vehicle running on gasoline achieves more miles per gallon than does the same vehicle running on a blend of gasoline and lower alcohol fuels.
Oxygenated fuels are blended to reduce harmful combustion emissions from petroleum-based liquid hydrocarbon gasoline, diesel fuel, jet fuel, lower distillate petroleum fuels, ground coke and coal solid hydrocarbons to reduce particulate soot, uncombusted hydrocarbons and carbon monoxide. Furthermore, larger quantities of a higher energy content, oxygenated alcohol fuel are needed than can be produced from grain, sugar cane, lignin and cellulosic batch fermentation of biomass.
In the broader energy field, there is also a growing need to inexpensively transport solid hydrocarbon materials such as coal and petroleum coke, and also heavy crude oils and bitumen from locations where they are produced to locations where they can be combusted or cleanly gasified for their thermal value. Transport by rail, truck or barge is costly and cumbersome.